Positron Emission Tomography (PET) devices employ positron-emitting radionuclides which are typically introduced into a subject, such as a patient, in a pharmaceutical composition. The positrons emitted by the positron-emitting radionuclides collide with the subject under investigation, resulting in the emission of pairs of gamma rays, which are detected. PET imaging devices are widely used to diagnose cancer recurrences, metastases of cancer, whether an early stage of cancer is present or not, and, if cancer has spread, its response to treatment. PET is also used in diagnosing certain cardiovascular and neurological diseases by highlighting areas with increased, diminished, or no metabolic activity.
Short-lived PET radionuclides suitable for use in PET devices include positron emitters having a half-life which is typically less than 5 days, and generally less than one day, such as Fluorine (F-18) (half-life 110 minutes), Carbon 11 (C-11) (half-life 20 minutes), Nitrogen 13 (N-13) (half-life 10 minutes), Oxygen-15 (O-15) (half-life 2 minutes), Iodine 124 (I-124) (half-life 4.2 days), Rubidium 82 (Rb-82) (half-life 75 seconds), Copper 64 (Cu-64) (half-life about 0.5 days), in quantities that are appropriate or required for dosing. Because of the short half-life of these radionuclides, they are unsuited to use in a calibration source for calibrating the PET device. Accordingly, PET calibration sources have been developed which include radionuclides which have a much longer half-life than the short-lived radionuclide used in imaging. These include radionuclides such as Germanium 68 (Ge-68) (half-life about 271 days) and Sodium 22 (Na-22) (half-life about 2.6 years). Methods have been developed to calibrate these long-lived radionuclides against the short-lived radionuclide. See, for example, U.S. Pat. No. 7,825,372 entitled SIMULATED DOSE CALIBRATOR SOURCE STANDARD FOR POSITRON EMISSION TOMOGRAPHY RADIONUCLIDES, and U.S. Pat. No. 7,615,740, issued Nov. 10, 2009, entitled SYRINGE-SHAPED DOSE CALIBRATION SOURCE STANDARD, both by Keith C. Allberg, the disclosures of which are incorporated herein by reference in their entireties.
One problem with the use of such calibration sources is that PET devices differ by manufacturer and facilities such as hospitals, often have two or more different PET devices. Thus a single calibration source often cannot be used to calibrate the different PET devices. A facility thus often has keep two or more different calibration sources in stock. Additionally, it is difficult to compare the results of two different PET devices, since this would require cross calibrating the two calibration sources at the same time.
There remains a need for a system and method for enabling a calibration source to be used interchangeably in two or more PET devices.